In an LTE (Long Term Evolution) system, the smallest time interval for a base station to schedule a user equipment is a subframe. Data transmission in an uplink direction is based on a policy of a synchronous (hybrid automatic repeat request, Hybrid Automatic Repeat reQuest) HARQ. Specifically, the base station sends uplink scheduling grant (Uplink_grant, UL_grant) information in a downlink subframe to schedule a physical uplink shared channel (Physical Uplink Shared Channel, PUSCH) in a certain subsequent uplink subframe; the user equipment (User Equipment, UE) sends the PUSCH according to the UL_grant; the base station receives the PUSCH, and sends feedback information (ACK or NACK) of the PUSCH, that is, physical HARQ indicator channel (Physical HARQ Indicator Channel, PHICH) information, at fixed timing, and negative PHICH information (that is, NACK) triggers PUSCH retransmission in a subsequent uplink subframe. Herein, after the base station schedules a PUSCH, timing of retransmitting a PHICH corresponding to the PUSCH and the PUSCH is fixed.
In LTE release 10, a carrier aggregation (Carrier Aggregation, CA) technology is introduced, so as to increase a peak rate of a system by supporting data sending on multiple carriers simultaneously. Two methods for scheduling uplink data, that is, non-cross-carrier scheduling and cross-carrier scheduling, are introduced in the LTE release 10. Because in the release 10, it is supposed that a primary cell (Pcell) and a secondary cell (Scell) adopting the CA technology adopt the same time division duplexing (Time Division Duplexing, TDD) uplink and downlink configuration, in the two scheduling policies, the primary cell and the secondary cell may work according to a timing relationship of an HARQ in an uplink and downlink configuration defined in an LTE release 8. For the non-cross-carrier scheduling, the UL_grant and the PHICH used to schedule a PUSCH of the Scell are sent by the Scell; and for the cross-carrier scheduling, the UL_grant and the PHICH used to schedule a PUSCH of the Scell are sent by the Pcell.
In LTE release 11, for a TDD system, it is necessary to study how to process different uplink and downlink configurations of multiple cells adopting the CA technology are different. For example, the PCell adopts an uplink and downlink configuration 1, and the SCell adopts an uplink and downlink configuration 2. For some subframes, a duplexing direction of the PCell and a duplexing direction of the SCell are consistent, for example, subframes 0 of the two cells are downlink subframes, and subframes 2 of the two cells are uplink subframes; however, for some special subframes, for example, a subframe 3 and a subframe 8, duplexing directions of the two cells are different.
For the foregoing circumstance that the uplink and downlink configurations of the two cells adopting the CA technology are different, if the non-cross-carrier scheduling is adopted, scheduling of PUSCH transmission of the Scell may still be performed according to timing of an uplink HARQ of the Scell. However, in the case of cross-carrier scheduling, because the UL_grant and the PHICH need to be sent by the Pcell, and a subframe of the Pcell used for timing for scheduling the PUSCH may be an uplink subframe, where and the timing is obtained according to a certain timing policy. The uplink subframe is incapable of supporting the cross-carrier scheduling of the PUSCH of the Scell, thereby failing to effectively implement the cross-carrier scheduling.